Turbo-feed pump assembly



Sept. 29, 1970 J, H, DALTRY El'AL TURBO-'FEED PUMP ASSEMBLY Filed Jan.28. 1969 \\\mmf United States Patent "ice 3,531,223 TURBO-FEED PUMPASSEMBLY John Harold Daltry and Geoffrey Bernard Thomas, Rugby, England,assignors to The English Electric Company Limited, London England, aBritish company Filed Jan. 28, 1969, Ser. No. 794,490 Claims priority,application Great Britain, Jan. 31, 1968, 4,952/ 68 Int. Cl. F04d 13/02,25/02 U.S. Cl. 417-409 7 Claims ABSTRACT F THE DISCLSURE Thisapplication is a copending application with our application Ser. No.794,489, filed Jan. 28, 1969.

This invention relates to turbo-feed pump assemblies.

According to this invention, a turbo-feed pump assem- 'bly comprises anelongated casing providing an inlet and outlet passage for the turbineat or near one of its ends and a part of a suction and delivery passagefor the feed pump towards its other end, said casing also having a boreformed therein which extends from the feed pump end thereof, a capsuleadapted to be located in said bore, and a shaft common to the turbineand the feed pump rotatably mounted in the capsule, one end of the shafthaving a turbine disc provided with at least one row of radiallyarranged axially extending blades which, when the capsule is located inthe casing, extends into a space between the turbine inlet and outletpassages and aligns with at least one row of stator blades carriedwithin said casing, said shaft also having at least one pump impellerwhich, when the capsule and shaft are in the located position, extendsinto the suction part of the feed pump passage, the arrangement 'beingsuch that the capsule and shaft as a complete unit can be inserted into,or withdrawn from, the feed pump end of said casing.

In order that this invention may be readily understood, a turbo-feedpump assembly constructed in accordance therewith will now be described,by way of example, with reference to the accompanying drawing, which isa somewhat diagrammatic sectional view through the upper half of theassembly.

Referring to the drawing, the assembly comprises a turbine unit 1 and afeed pump unit 2. The casing 3 of the turbine unit is of annular formand has a steam inlet passage 4 which extends along an axial centre linethrough the assembly to an annular nozzle box 5 having a number ofradially-directed nozzles 6 spaced therearound. The nozzles 6 directsteam through a two-stage velocity compounded radial turbine arrangementwhich comprises a row of stator `blades 7 disposed within and carried bythe turbine casing 3, and two rows of rotor blades 8 carried by aturbine disc 9, said blades 7 and 8 extending axially with respect tothe assembly. After passing through the turbine arrangement, the steamis fed through a dilfuser 11 into an annular exhaust chamber 12 which isprovided with two exhaust ducts 13, said ducts being disposed directlyopposite to each other.

The turbine casing 3 has a flange 14 which is bolted and spigotedsolidly on to a mating flange 15 forming 3,531,223 Patented Sept. 29,1970 part of an annular feed pump casing 16, thus ensuring alignment ofthe two units.

An axial bore extends throughout the feed pump casing 16, this borebeing defined by the dotted line 17 and solid line 18 in the drawing,and is in alignment with a further bore 20 within the turbine casing 3.A capsule 19 is adapted to be inserted into these bores through anopening 21 in the outer end of the feed pump casing 16 and to be locatedtherein by wedge members 22 and a split ring 23. The wedge members 22act between the flange 15 of the feed pump casing and a slanted face 24provided on the capsule 19. These wedge members ensure that no movementtakes place between the capsule 19 and the turbine and feed pump casings3 and 16 respectively and are held in place by suitable tie bolts (notshown). The split ring 23 is located in an annular groove 25 formed inthe feed pump casing 16 adjacent the opening 21 and engages the outerend of the capsule 19.

The capsule 19 is a circular steel casing and includes an intermediateportion 26 of the suction passage for the feed pump. A shaft 27 extendsthrough the capsule and is rotatably mounted in journal bearings 28, 29and 29A, which are conveniently made of carbon impregnated with copper.This shaft carries two pump impellers 30 which extend into theintermediate portion 26 of the feed pump suction passage and a 'balancepiston 30A, and the inner end of the shaft has the turbine disc 9 formedintegrally therewith. That part of the capsule 19 which extends into thebore 20 within the turbine casing 3 is sealed by a pair of piston rings31. The shaft 27 is maintained in position within the capsule 19 by aback stop bearing 32 which engages one face of a thrust ring 33, and theother face of said thrust ring has a thrust bearing 34 associatedtherewith. The thrust bearing, which conveniently also acts as a seal toprevent steam escaping into the chamber 43, is arranged with sixcavities 35 spaced therearound and each of said cavities is fed withfluid which in this embodiment is water at high pressure via ducts 36eX- tending through an annular 'bearing block 37 for the thrust bearing.Said high pressure fluid is fed to the ducts 36 from a source not shown,via pipes 38. This high pressure fluid leaks from the cavities 35, asshown by the arrows in the drawing, into an annular chamber 39 andthence to a return duct 41 by the action of a thrower 42 formed aroundthe periphery of the thrust ring 33, and said iluid also leaks into afurther annular chamber 43 via the mating surfaces of the shaft 27 andbearing 28, and thence into said intermediate portion 26 of the feedpump suction passage via the mating surfaces of said shaft and bearing29, thereby providing for lubrication of said bearings 28 and 29. Thebearing 'block 37 carrying the thrust bearing 34 is urged towards thethrust ring by a spring ring 44.

The ring 44 permits the thrust bearing 34, via the bearing block 37, tomaintain a parallel relationship with the thrust ring 33 on the shaft27. Thus, such an arrangement caters for any misalignment of the shaftwhich may occur during continued operation of the assembly, for example,due to distortion of the capsule 19.

As an alternative to providing for lubrication of the journal bearing 28by fluid leaking from the cavities 3-5 of the thrust bearing 34, diuidunder pressure may be fed directly to the bearing surface of saidbearing, for example, by a branch duct leading from the duct 36, or by aseparate duct provided with its own feed pipe 38. In such an arrangementany fluid which leaks from the thrust bearing 34 towards the journalbearing 28j and vice versa is conveniently collected in a space betweenthe two bearings and drained into the annular chamber 43 by drainageducts suitably formed in the bearing block 37.

Turning now to the feed pump unit 2, when the capsule J 19 is located inposition within the assembly, the intermediate portion 26 of the suctionpassage aligns with an annular inlet chamber 45 for said suction passageand a discharge outlet 46, these latter being formed within the feedpump casing 16.

It will be appreciated that the capsule 19 may be readily dismantledfrom the assembly by disconnecting the supply pipes 38 from the capsulebody, withdrawing the wedge members 22 from their wedging position, andby removing the split ring 23. This permits the complete capsule to bewithdrawn from the turbine and feed pump casing through the opening 21,and since said capsule carries the rotor blades for the turbine, thethrust bearing arrangement and the majority of the working componentsfor the feed pump, these parts are readily accessible for servicing.

In the embodiment described above, separate casings are provided for theturbine and feed pump units 1, 2 respectively. However, it will beappreciated that a turbofeed pump assembly in accordance with theinvention may be formed as an integrated assembly and that a singlecasing may be employed to house these units.

In a modification of the embodiment described above, the back stopbearing 32 may be replaced by a further thrust bearing which is biasedtowards the thrust ring 33. lIn order to lubricate this further thrustbearing, a duct would be provided in the body of the capsule 19 leadingfrom the feed pipe 38 to said further thrust ring.

We claim:

1. A turbo-feed pump assembly comprising an elongated casing providingan inlet and outlet passage for the turbine at or near one of its endsand a part of a suction and delivery passage for the feed pump towardsits other end, said casing also having a bore formed therein whichextends from the feed pump end thereof, at least one row of statorblades within said casing, a capsule adapted to be located in said bore,a shaft common to the turbine and the feed pump rotatably mounted in thecapsule, a turbine disc at one end of the shaft, at least one row ofradially arranged axially extending blades provided on said turbinedisc, which, when the capsule is located in the casing, extends into aspace between the turbine inlet and outlet passages and aligns with saidrow of stator blades, and at least one pump impeller mounted on saidshaft which, when the capsule and shaft are in their located position,extends into the suction part of the feed pump passage, the arrangementbeing such that the capsule and shaft as a complete unit can be insertedinto, or withdrawn from, the feed pump end of said casing.

2. A turbo-feed pump assembly according to claim l, wherein the capsulehas part of the suction part of the feed pump passage formed therein,into which the pump impeller extends.

3. A turbo-feed pump assembly according to claim 1, wherein the casingis in two parts comprising a turbine casing and a feed pump casingrespectively, said casings being connected together via mating anges,said bore extends completely through the feed pump casing and partwaythrough the turbine casing.

4. A turbo-feed pump assembly according to claim 3, wherein the capsuleis held in its located position within the casings by wedge membersacting between feed pump casing ange and a slanting face formed on thecapsule.

5. A turbo-feed pump assembly according to claim 1, wherein the shafthas a thrust ring adjacent the turbine disc, and the capsule has anannular member which carries a thrust bearing ring for the thrust ringand a journal bearing for the shaft, the annular member being slidableon said capsule and being biased so that its thrust bearing is urgedtowards one side of the thrust ring.

6. A turbo-feed pump assembly according to claim 5, wherein means areprovided for feeding lubricating fluid under pressure to the thrustbearing, and the journal bearing is arranged to be lubricated by fluidleaking from the bearing surface of said thrust bearing.

7. A turbo-feed pump assembly according to claim 6, wherein a furtherthrust bearing is located on the Other side of the thrust ring and isarranged to receive lubricating fluid under pressure from the fluidfeeding means.

References Cited UNITED STATES PATENTS 6/1961 Wise 103-87 XR 8/1965 LaFleur 230-116 U.S. Cl. X.R. 415--105, 219

